A carbon fiber based tin-silver-copper alloy matrix composite (CF-TIM) was developed via electrospinning of a mesophase pitch with polyimide and carbonization at 1000 °C, followed by sputter coating with titanium and gold, and alloy infiltration. The carbonized fibers, in film form, showed a thermal conductivity of ∼4 W m-1 K-1 and the CF-TIM showed an anisotropic thermal conductivity of 41 ± 2 W m-1 K-1 in-plane and 20 ± 3 W m-1 K-1 through-plane. The thermal contact resistance of the CF-TIM was estimated to be below 1 K mm2 W-1. The CF-TIM showed no reduction in effective through-plane thermal conductivity after 1000 temperature cycles, which indicates the potential use of CF-TIM in thermal management applications.

ere we review the concepts and technologies, in particular photochemical gating, which contributed to the recent progress in quantum Hall resistance metrology based on large scale epitaxial graphene on silicon carbide.

The quantum Hall effect(1) allows the international standard for resistance to be defined in terms of the electron charge and Plancks constant alone. The effect comprises the quantization of the Hall resistance in two-dimensional electron systems in rational fractions of R-K = h/e(2) = 25 812.807 557(18) Omega, the resistance quantum(2). Despite 30 years of research into the quantum Hall effect, the level of precision necessary for metrology-a few parts per billion-has been achieved only in silicon and III-V heterostructure devices(3-5). Graphene should, in principle, be an ideal material for a quantum resistance standard(6), because it is inherently two-dimensional and its discrete electron energy levels in a magnetic field (the Landau levels(7)) are widely spaced. However, the precisions demonstrated so far have been lower than one part per million(8). Here, we report a quantum Hall resistance quantization accuracy of three parts per billion in monolayer epitaxial graphene at 300 mK, four orders of magnitude better than previously reported. Moreover, by demonstrating the structural integrity and uniformity of graphene over hundreds of micrometres, as well as reproducible mobility and carrier concentrations across a half-centimetre wafer, these results boost the prospects of using epitaxial graphene in applications beyond quantum metrology.